I was thinking if you are just working in the shorter ROM where the muscle is contracted then you would be able to lift heavier but for less reps correct? i was thinking this because when you are working in the full ROM theres a point where you are stressed and contracted (thanks gary) so if you are constantly contracted you are missing out in the 1-2 seconds of "rest". For example a bicep curl, at the bottom of the curl when your arm is almost fully extended the muscle is stressed but not contracted and therefore you get a slight break before returning back to the curl and contracting the muscle fully. So you would therefore fatigure faster and tear the muscle and in turn develop growth but not strength like IW mentioned.
Hopefully that made sense because i was typing as i was thinking. Anyways my bf tried it out in the gym today and he said that he felt like he got a better workout and could definitely lift heavier and get the same number of reps. However, from what the responses are....it sounds like full ROM is still the better option.

thanks guys!